Monday, January 7, 2013

All the LDP-1450 text modes explored

I wrote a program to rapidly cycle through all possible text modes for the LDP-1450 laserdisc player.  The mode number is in hex and comes right after the 'M'.  X and Y position is fixed at 10x10 (0Ax0A in hex).  The trailing characters are leftover from earlier tests, but this illustrates that the entire text buffer must be cleared out or else it will be displayed.

NOTE : in order to display modes when a blue background is not present, a disc must be playing.  (if no disc is in the machine, it won't show anything)

As you can see, this is very helpful in determining what each bit of the mode byte means.  I haven't dug into this much yet but it is pretty apparent that some bits represent width and some bits represent height.

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